DR. D. EERRIER ON THE BRAIN OE MONKEYS. 
443 
stimulation of these regions produced. The animal was allowed to recover consciousness 
completely at 5 p.m. It remained for two hours as well as before to all appearance. 
At 7 p.m. by means of the blowpipe cautery the surface of the postero-parietal 
lobule (foot-centre), of the ascending parietal (hand and wrist centre), with a small 
portion of the upper extremity of the ascending frontal convolution (arm and leg 
centres) were destroyed. 
Though the animal was quite conscious it expressed no sign of pain or uneasiness 
during the process. Once during the passage of the cautery along the ascending 
parietal convolution a partial closure of the fist occurred, seeming as if the heat had 
caused in some degree the same effect as the electric stimulus. 
On being set free the animal jumped away, but staggered and fell over on its right 
side. It was observed that when the animal moved, it did so by the aid of the left arm 
and left leg, dragging the right leg on the floor. When it rested, the right leg was 
seen to straddle outwards, as if the power of adduction had been lost. There was no 
muscular resistance to the free movement of the ankle in any direction, but there was 
resistance to forcible extension of the leg. The right arm was kept flexed at the elbow, 
but the wrist dropped and the hand hung flaccid. There was no resistance offered to 
flexion and extension of the wrist, but decided muscular resistance to straightening 
the arm. The animal made no use of its right hand to grasp, or in progression, but it 
retained the power of flexing the right forearm. 
The sensibility of the right side was unimpaired, as judged by the expression of pain 
and annoyance when the limbs were pricked or pinched. 
The great difficulty it experienced in walking, or sitting steadily upright, caused 
the animal to growl in annoyance each time it staggered. 
Otherwise the animal was well, and ate and drank as before within an hour after the 
operation. 
The animal was then subjected to an experiment for destruction of the angular 
gyrus (see Exp. VIII.), and its further history and the results of the post mortem 
examination are detailed under Exp. VIII. 
This experiment demonstrates very conclusively that the destruction of cortical centres, 
irritation of which by the electric stimulus gave rise to very definite movements of the 
hand and foot, caused motor paralysis of the same movements and of none other ; and, 
as will be found, the paralysis remained permanent up till the time of death. 
Experiment VI. 
February 26 th, 1875. — A monkey was chloroformed, and the left hemisphere was 
exposed on the region which former experiments had indicated as the centre for the 
biceps (/, fig. 8). By electrical irritation the region was accurately defined, and the 
grey matter destroyed by means of the blowpipe cautery. The animal was conscious, 
and lay perfectly quiet during the operation, though unbound. When placed on the 
floor the animal sat very unsteadily ; and the cause of this was seen to be that the right 
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